Because of the world's increasing demand for petroleum products, it has been desirable to find alternative hydrocarbon feedstocks for fuel. For example, it is known to convert coal to liquid fuels using a family of processes known as coal liquefaction. Such processes are disclosed in, for example, U.S. Pat. No. 4,487,683, the disclosure of which is fully incorporated herein by reference. It is also known to upgrade liquid hydrocarbon to fuel-quality products. Such processes are disclosed in, for example, U.S. Pat. No. 7,022,505, the disclosure of which is fully incorporated herein by reference.
Most of the traditional methods of coal liquefaction have significant energy requirements and environmental impact. Conventional techniques for direct coal liquefaction will generally result in lower CO2 emissions compared to indirect techniques, but will typically require relatively higher temperatures and higher pressure to enable liquefaction reactions and hydrogen transfer from the hydrogen donor to obtain significant product yield and quality. Ideally such a process would be highly flexible in that it should readily admit to operation on small, medium and large commercial scale.
One method that offers the potential to process hydrocarbon fuels at lower environmental costs than existing commercial systems utilizes plasma processing. In plasma processing, hydrocarbons are fed into a reaction chamber in which they are ionized to form plasma, for example by exposure to a high intensity field. In the plasma state the constituents of the feed material are dissociated and may either be extracted separately, recombined or reacted with additional feed materials, depending on the required output product. Electromagnetic-induced plasmas, in particular, offer the potential for highly efficient cracking of both gas and liquid feed materials due to superior energy coupling between energy source, plasma and feedstock. Such plasmas have been shown to have a catalytic effect, as a result of coupling between the electromagnetic, particularly microwave, field and the feed material, that increases the rate of reaction, which in turn reduces the time for which the feed material must be maintained in the plasma state, i.e. the residency time.
It is, however, difficult to scale up reaction chambers that use microwaves generated for commercial plasma operations, and many current liquefaction and hydrocarbon upgrading processes are practically and/or economically unable to meet the scale required for commercial production. Accordingly, improved systems for converting and upgrading hydrocarbon fuel products are needed.
This document describes methods and systems that are directed to the problems described above.